Patent Document 1 given below has made publicly known an FM•CW radar system of a type which is designed: to alternately transmit an FM•CW wave and a CW wave in a case where one of an increase side peak signal and a decrease side peak signal of an object existing within a close range is missing; and to calculate a distance and a relative speed of the object on the basis of a peak frequency of the other which is not missing on the FM•CW wave and a peak frequency on the CW wave.
Furthermore, Patent Document 2 given below has made publicly known an FM•CW radar system of another type which is designed to calculate a distance and a relative speed of an object by interpolating one from the other of an increase side peak signal and a decrease side peak signal of the object in a case where one of the increase side peak signal and the decrease side peak signal is buried in low-frequency noise.